1. Field of the Invention
The present invention relates to new derivatives of penem and pharmaceutically acceptable salts thereof having an excellent antibiotic activity.
2. Description of the Prior Art
In general, infectious diseases are caused by pathogenic microorganisms which are fixed in a certain portion of a living body and propagate therein and take place local reactions, when the microorganism accidentally penetrates into the living body and so forth. One of effective therapies for infectious diseases is to administrate an antibiotic to patients suffering from such disease. As such effective antibiotics conventionally used widely, there have been known such as penicillin, cephalosporin antibiotics having a wide antibacterial spectrum and these antibiotics have widely been used for treating various kinds of infectious diseases and exhibited an excellent effect.
Thus, in most of cases, the pathogenic microorganisms are eradicated by the action of a chemotherapeutic agent and patients are recovered. However, it is well known that a microorganism causing the corresponding infectious disease sometimes acquires resistance to the medicine, therefore if it is used for a long period of time and this becomes an inevitable problem in chemotherapy.
As a result, the antibiotics such as penicillin and cephalosporin antibiotics have not sufficiently been satisfiable in antibacterial spectrum, antibacterial activity, behavior in the body to which antibiotic is administered or safety, due to the appearance of the resistant bacteria during the long term and wide-spread application thereof.
Under such circumstances, an antibiotic called thienamycin was developed (see J. P. Laid-Open No. 73191/76), which shows sensitivity against bacteria resistant to penicillins and cephalosporin antibiotics and then studies on the synthesis of carbapenem derivatives and other penem derivatives having a skeletal structure similar to that of carbapenem have energetically been effected. However, these conventionally developed or synthesized carbapenem or penem antibiotics are not satisfied because of different drawbacks such that they are all physicochemically unstable and easily suffer from the enzymatic decomposition by emzymes such as dehydropeptidase in the kidney and further they have a rather low and insufficient solubility to water. Thus, there has not yet been developed even one highly valuable or effective medicine.